reply to post by Stargate2012
For sure? No, nothing is 100% certain (except perhaps death and taxes).
However, past experience tells us that it's much more likely that the scientific predictions we make will be close to, if not "right on the
If that were not so, then we could not have predicted previous meteor shower peaks to within minutes of the actual observed times, and we could not
have launched probes years in advance to intercept asteroids/comets at exactly the right place/time... but we have...
Orbital/celestial mechanics is a fine art which we have become very good at, and although there is always a small
chance that nature could
throw a spanner in the works, that possibility is vanishingly small due to space being mostly empty space. Again, our observations confirm this. If
they did not I would be worried too!
We also get better at it every time a new observation of a comet/asteroid/meteor shower is made, as well as diminishing the odds that nature could
throw a spanner in the works, by hunting down ever smaller/further away objects that lurk in space. Ultimately, if nature does throw a curve ball in
the form of a new comet kicked out of the Oort cloud for example, the odds of the two objects coming close enough to alter each others orbit
significantly are significantly worse than launching two rowing boats, one from the US East coast, and another from Lands End in the UK, and having
them run into each other half way across whilst trying to row them to each others launch sites.
Space is on an even vaster scale, and relatively large objects, can easily miss each other. If you performed the above experiment 100 times over, you
probably would not get a hit, but perhaps you would if performed it a few million times.
Going back to the possibility of there being larger objects lurking in the Draconid meteor stream, if there were any that could hit us they would be
from a different dust trail/orbit than the 1900 trail (which is still highly unlikely since we can "run back time" in our orbital simulations, so it
would have been spotted that we were crossing another trail).
Imagine an open top truck (comet) piled high with feathers (meteoroids), driving very slowly along a road (orbit) with a slight but constant breeze
blowing (solar wind/AKA solar radiation pressure) at a 90 degree angle to the road.
As you'd imagine, most of the feathers that came off the truck would end up piled up along the road side verge (earth's orbit), and very few would
remain actually on the road. Now if a couple of dead birds (large comet fragments) fall off the back of the truck, they will stay on the road, since
the wind is not strong enough to affect them significantly. Since earth does not cross the "road", where all the big bits are, there is not much
danger from us running into a dead chicken, although we may well be swamped with feathers!
My advice is go out and watch the feathers, as it's rare to see so many in such a short space of time, and don't worry too much about chickens, as
they are very rare, although you might see the odd drumstick if you are lucky